chem 105x monday, dec. 5, 2011 -...
TRANSCRIPT
Chem 105X Monday, Dec. 5, 2011 Chapter 10, Kotz Organic Chemistry Alkynes More on hydrocarbons and petroleum products Oxidation states, and oxidation numbers, of carbon O-containing functional groups Course questionnaires
12/5/2011 1
Review for final: 201 Reichardt Sunday 12-11-11 , 4-6 PM Keller (Stoichiometry) Monday 12-12-11 , 6-8 PM Heitzler (Lewis formulas, VSEPR etc)
Review for final: 509 Gruening Saturday 12-10-11 , 2-4 PM Quinn Sawyer Tuesday 12-13-11 , 5-7 PM Quinn Sawyer
12/5/2011 2
C C C H 3 C H 2 C H 2
C H 2 C H
C H 3
C H 3
C CH3C CH2
CH2 CH
CH3
CH3
1 2 3 4
5
6 7
7-methyl-3-octyne
8
The common name of H-C≡C-H is “acetylene”
(“ethyne” is the systematic name, but is not used.)
Uses: acetylene is welding gas
larger alkynes used as synthesis intermediates because
the C≡C bond can be modified in many ways.
Some natural molecules such as dynemicin anti-cancer
drug contain C≡C bonds.
12/5/2011 3
Alkynes are used in organic synthesis reactions to
create specific isomer products.
CH3C C H + Base CH3C C + HBase
CH3C C CH2CH2CH3
Cl
CH3C C CH2CH2CH3 + Cl
C H 3 C C C H 2 C H 2 C H 3
C l
C H 3 C C C H 2 C H 2 C H 3 + Cl
C H 3 C C H + Base C H 3 C C + HBase
acetylide ion
2-hexyne
C-C bond forming reactions like this are used to make larger, more complex molecules. This is the main goal of organic chemistry: synthesis of new molecules and materials.
N
H H
How many alkyne isomers exist having a formula of C6H10?
Each should contain one CC bond.
four
five s
ix
sev
en
32
16
2931
1. four
2. five
3. six
4. seven
1 2 3 4 5 6 7 8 9 10 11 12 13 14
1
15
29
43
57
71
85
99
113
127
141
155
169
183
183
197
12/5/2011 6
How many alkyne isomers exist having a formula of C6H10?
Each should contain one CC bond.
1. four
2. five
3. six
4. seven
CC C C C C
CC C C C C
CC C C C C
CC C C C
C
CC C C C
C
CC C C C
C
CC C C
C
C
6 in a row
5 in a rowtriple at end
5 in a rowtriple at C2
4 in a row
On board
12/5/2011 8
See 2Hexanes.hin
Short-range attractive forces stick surfaces together. Hence, higher BPs for larger molecules.
Hydrocarbons can be separated by gas chromatography (GC). Last week in lab students used a GC-MS instrument. This uses a mass spectrometer (MS) to identify and characterize the molecules as they exit the separation column.
GC
MS
12/5/2011 17
Oxygen–containing functional groups (sp3 O)
Alcohol ethanol C
O H C
H O H
H H
H H
Ether Diethyl ether
OH H
O H H
OC C
O C C
OH3C CH3
O H 3 C C H 3
12/5/2011 18
Carbonyl (C=O)–containing functional groups
Ketone
Aldehyde
Carboxylic acid
acetone (propanone)
O
C C
O
C C H
H
H
H
H H
O
C H
O
C H
H
H
H acetaldehyde (ethanal)
O
C O H
O
C H H
H
O H acetic acid (CH3CO2H)
12/5/2011 19
Carbon oxidation numbers in different compounds can range from -4 to +4 (here, -3 to +3).
ethanol acetaldehyde acetic acid
+1
+1
+1
+1 +1
+1 +1
+1
-2
-2 -2
-2
+1 +1
+1 +1 +1
+1
-3
This C is
like C in
ethane.
-3 -3 -1
+1 +3
2-electron oxidation
2-electron oxidation
C O
H
C H 3
H
H
C
O
H 3 C
H
C
O
H 3 C
O H
C
H
H
H
C
H
H
H+1
+1
+1 +1
+1
+1
-3
-3
C
H
H
H
C
H
H
H +1
+1
+1 +1
+1
+1
-3
-3
Recall: H is almost always +1 SUM ox # = total charge
What are the oxidation numbers of methane and carbon dioxide, respectively?
-4, +
4
+4,
-4
0, +
8
-8, 0
61
3
14
31
1 2 3 4 5 6 7 8 9 10 11 12 13 14
1
15
29
43
57
71
85
99
113
127
141
155
169
183
183
197
1. -4, +4
2. +4, -4
3. 0, +8
4. -8, 0
12/5/2011 22
C H 2 C H 2 C H 3 C H 2 O H
+1 +1 +1 +1 +1
-2 -2
-2
-3 -1
This carbon is oxidized (Ox # increases algebraically)
This carbon is reduced (Ox # decreases algebraically)
Net effect: zero. Oxidation balances reduction in alkene hydration.
A typical organic reaction: Hydration (addition of water ) of ethylene. Analyzing organic reactions using oxidation numbers.
H-OH
12/5/2011 23
You should be able to identify some functional groups within larger, more complex organic molecules.
CH3
H3C CH3
CO2H
C H 3
H 3 C C H 3
C O 2 H
carboxylic acid
alkane
aromatic
Ibuprofen
12/5/2011 24
Paclitaxel (Taxol) (core molecule) - Discovered in bark of Pacific yew tree (1968) and in various fungi Anti-cancer drug Commercially produced by bacterial fermentation Synthesized by several chemistry labs.
C31H38O11
Alcohol Ester Aromatic
Alkane Alkene
ether
Some drug molecules, like paclitaxel , have a complex 3-dimensional structure. Their large, varied surface allows them to bind to specific sites or protein targets . Paclitaxel (taxol) binds to the tubulin protein inside cells.
See paclitaxel.hin
Electrostatic potential 3D-mapped isosurface